Normally-Ordered Time Evolution Operator for Mass-Varying Harmonic Oscillator and Wigner Function of Squeezed Number State

For investigating dynamic evolution of a mass-varying harmonic oscillator we constitute a ket-bra integration operator in coherent state representation and then perform this integral by virtue of the technique of integration within an ordered product of operators. The normally ordered time evolution operator is thus obtained. We then derive the Wigner function of u（t）｜n,〉, where ｜n〉 is a Fock state, which exhibits a generalized squeezing, the squeezing effect is related to the varying mass with time.     

Operator Formulas Involving Generalized Stirling Number Derived by Virtue of Normal Ordering of Vacuum Projector

By virtue of the normal ordering of vacuum projector we directly derive some new complicated operator identities, regarding to the generalized Stirling number.     

Preserving Coherence of Coherent State Studied via Weyl-Wigner Correspondence

By means of the Weyl correspondence and the explicit normally ordered expression of the Wigner operator we convert the time evolution equation of coherent states, governed by some Hamiltonian operators, into seeking for consistent solution of a set of evolution equtions of classical variables which can meet the requirment that an initial coherent state remains coherent all the time.     

Evolution of a Thermo Vacuum State in a Single-Mode Amplitude Dissipative Channel

We investigate how an initial thermo vacuum state, in the context of thermo field dynamics, evolves in a single-mode amplitude dissipative channel, and find that in this process the thermo squeezing effect decreases while the fictitious-mode vacuum becomes chaotic.     

Squeezing-Displacement Dynamics for One-Dimensional Potential Well with Two Mobile Walls where Wavefunctions Vanish

We show that the dynamics/or a particle confined in a one-dimensional potential well with two mobile boundaries where wavefunctions vanish can be converted to the case as if the boundary was time-independent at the expense of an appropriate time-dependent Hamiltonian. The squeezing-displacement operator can be derived, and the corresponding Flamiltonian is determined by the situation of mobile boundaries.     

用Weyl-Winger对应求证相干态的一个重要性质

一般而言,一个量子算符只有其在某个表象中所有的矩阵元都知道了才能被确定.可是当一个量子算符的相干态平均值(对角表示)知道了,这个算符本身就确定了,这是一个值得注记的性质.本文用Weyl-Winger对应的唯一性证明这一性质.     

New formulas for normalizing photon-added（-subtracted） two-mode squeezed thermal states

For the first time,we derive the compact forms of normalization factors for photon-added(-subtracted) two-mode squeezed thermal states by using the P-representation and the integration within an ordered product of operators(IWOP) technique.It is found that these two factors are related to the Jacobi polynomials.In addition,some new relationships for Jacobi polynomials are presented.     

Decoherence of photon-subtracted squeezed vacuum state in dissipative channel

This paper investigates the decoherence of photo-subtracted squeezed vacuum state (PSSVS) in dissipative channel by describing its statistical properties with time evolution such as Wigner function,Husimi function,and tomogram.It first calculates the normalization factor of PSSVS related to Legendre polynomial.After deriving the normally ordered density operator of PSSVS in dissipative channel,one obtains the explicit analytical expressions of time evolution of PSSVS’s statistical distribution function.It finds that these statistical distributions loss their non-Gaussian nature and become Gaussian at last in the dissipative environment as expected.     

Evolution of a two-mode squeezed vacuum in the amplitude dissipative channel

For the first time we derive the dissipating result of an initial two-mode squeezed pure vacuum state passing through a two-mode amplitude dissipative channel described by the direct product of two independent single-mode master equations. Although these two master equations do not mix the two modes (there is no coupling between them), since the two-mode squeezed state is simultaneously an entangled state, the final state which emerges from passing this channel is a two-mode mixed density operator. The compact expression of the outcoming state is obtained, which manifestly shows that as time evolves, the squeezing effect decreases.     

A new theorem relating quantum tomogram to the Fresnel operator

According to Fan-Hu's formalism (Fan Hong-Yi and Hu Li-Yun 2009 Opt. Commun. bf282 3734) that the tomogram of quantum states can be considered as the module-square of the state wave function in the intermediate coordinate-momentum representation which is just the eigenvector of the Fresnel quadrature phase, we derive a new theorem for calculating quantum tomogram of density operator, i.e., the tomogram of a density operator ρ is equal to the marginal integration of the classical Weyl correspondence function of F⁺ρF, where F is the Fresnel operator. Applications of this theorem to evaluating the tomogram of optical chaotic field and squeezed chaotic optical field are presented.